Metal coated glass fiber and method of its formation



H. R. NACK 2,791,515

METAL COATED GLASS FIBER AND METHOD OF ITS FORMATION May 7,1957

Filed Aug. 14, 1953 i NH NN W. mR M M E H m N m T A United States Patent" METAL COATED GLASS FIBER AND METHOD OF ITS FORMATION Herman R. Nack, Troy, Ohio, assignor to The Commonwealth Engineering Company of Ohio, Dayton, Ohio, a corporation of Ohio Application August 14, 1953, Serial No. 374,352

11 Claims. (Cl. 117-71) This invention relates to a novel gas plating process and to the product thereof.

This application is related to copending application of Howard J. Homer and Herman R. Nack, Serial No. 289,828, filed May 24, 1952, now Patent No. 2,749,255, and co-pending application of Herman R. Nack and John R. Whitacre, Serial No. 324,961, filed December 9, 1952, each assigned to the same assignee as the present invention.

It has now been found that if siliceous material such as glass fibers is treated with a chrome complex of the Werner type prior to the deposition on the material of metal from the gaseous state that a superior product is achieved. For example, where the metal is deposited by the decomposition of iron pentacarbonyl the metallic film over the chrome complex coating remains lustrous over a long period of time even though exposed to humid atmospheres. In one instance a large sample of the material exposed to normal climatic conditions, temperature, humidity, etc, showed no decrease in luster over a three month period, and none of the material exhibited any deterioration including the property of electrical conductivity.

Other metals are equally useful particularly nickel, but the advantages of the process are most particularly noted with respect to iron which normally would be expected to deteriorate rapidly when in thin film form when exposed to the atmosphere.

It is accordingly :1 primary object of this invention to describe a novel gas plating process for siliceous materials particularly glass fibers, which process results in the deposition of a highly adherent film from a gaseous heat decomposable metal bearing compound.

It is another object of this invention to describe a novel product which resists the attack of atmospheric conditions and is particularly efficacious with respect to ferrous type materials.

These and other allied objectives of the invention are attained by first coating the siliceous base, which is subjected to the heat decomposable metal bearing gas, with a compound of the Werner type in which methacrylate is coordinated with chromium; this coated siliceous base is then heated and the heat decomposable metal bearing compound is caused to contact the heated base and to deposit metal.

The preferred Werner complex is methacrylato chromic chloride which adheres well to siliceous bases, particularly glass fibers; the heating of this Werner complex when the temperature of the base is raised to prepare it for presentation to the gaseous compound apparently accomplishes a dehydration resulting in the formation of Cr-O-Cr linkages.

The metals deposited on the treated base adhere well thereto. The exact mechanism of the reaction which takes place between the glass fibers or other siliceous base, the chrome complex and the material deposited from the gaseous state is not well understood, but the reaction is clearly obviously effective with respect to iron to inhibit rust.

The process is itself carried out under vacuum conditions; the product of the procedure retains substantially all of the flexibility and other physical characteristics of the original material, for example, glass fibers even though coated to a considerable extent with a metallic film over the chrome complex is highly lustrous, flexible and resistant to high temperatures.

The process of invention is applicable particularly to glass fibers and may be carried out with fibers fresh from the forming process or with fibers which have been gathered into rovings, yarn or cloth forms. Preferably where binders have been applied to the glass they are removed in a washing or heating prior to the chrome complex application in order that optimum adhesions will be achieved.

The operating pressures for the operation of plating may vary over wide ranges from the sub-atmospheric to the atmospheric, but it is generally preferred to employ relatively low pressures, as low as a tenth of a millimeter of mercury. Operation under atmospheric conditions simplifies the apparatus somewhat with respect to scaling, but considerable caution must be exercised. to exclude oxygen and water vapor from the air since under alkaline conditions iron pentacarbonyl reacts with water to set hydrogen free. Such hydrogen may then combine with the carbonyl to form a hydride. The alkali which would promote this reaction is present on the surface of many glasses to such an extent as to require considerable caution to preclude the possibility of such reaction, and care should be most particularly exercised on an alkali glass of fine fiber form is employed as leaching then occurs rather readily.

The invention will be more fully understood by reference to the following detailed description and accompanying drawing wherein Figure 1 illustrates schematically the apparatus useful in the process.

Figure 2 illustrates in cross-section a glass fiber or filament which has been treated with the chromium containing coating composition and gas plated with nickel using nickel carbonyl.

Referring to the drawing there is shown at 1 a cylinder containing carbon dioxide under pressure, the cylinder being equipped with a valve 2 and a gauge 3 for indicating the flow of gases through a line 5 terminating in "a coil 7 as at 9. Secured to the upper end of the coil 7 is an exit conduit 11 having a check valve 12 and terminating in a U-shaped conduit member 13.

A gas plating chamber 17 is secured to the other end of line 15 and is itself provided with a gas outlet 19 and longitudinally opposed openings 21, 23 for the passage of a substantially continuous length of roving of glass fibers 24.

A tubular heater 25 is connected through opening 21 for heating of the chrome complex coated glass fiber in its passage to the plating chamber. Chamber Z7 is itself surrounded by an induction heating coil 29 which maintains the same sufficiently hot during the plating operation to provide a gaseous atmosphere of the carbonyl; this heater also maintains the temperature of the glass fiber roving sufiiciently high by radiation-to insure of thermal decomposition of the carbonyl when it contacts the glass.

At the opening 23 of chamber 17 (left hand end) a casing 31 houses a shaft 33 carrying an eccentric 35 driven through a mechanism (not shown). The eccentric 35 in the course of its revolutions contacts the roving 24 setting the same into rapid vibration over the free length thereof thereby causing the same to open up into strands, and the strands into filaments, to expose the roving quite completely to the atmosphere of the chamber 17. The filaments and strands, after plating, in their passage through seal 37, reconverge to their original form. A similar vibration apparatus is described in the co-pend-ing application referred to hereinbefore.

Seal 37 consists merely of a chamber of metal or heavy rubber having an outlet 39 for the passage of roving 24 and an inlet line 41 for the passage of a carrier or other gas such as carbon dioxide from a suitable source 43. The fiow of, for example carbon dioxide, is regulated by hand valve 45 adjacent gage 47 to provide a sufficient quantity of gas at 37 and 31 to prevent any carbonyl flow thereto. Thus the carbon dioxide will itself flow whether or not vacuo conditions obtain with the plating gas to chamber 17. A second and similar gas seal 49 is indicated generally at the right hand of heater tube 25 and prevents air from being drawn into the system.

The gases flowing from chamber 17 may be exhausted under the influence of vacuum through outlet line 19 which terminates in a condensing coil 59 immersed in Dry Ice or other refrigerant 50. The condenser coil is provided with a return line 51 through which liquid iron pentacarbonyl may flow to lines 11 and 13 for recycling to the plating chamber. The pressure of the gases in coil 49 as they are being drawn therethrough will tend to force the liquid carbonyl in line 51 through check valve 52 which prevents gas flow to the coil from the source. When operated at atmospheric pressure some exhaust gases may be recycled but this is not detrimental.

The condensing coil 49 is also connected by conduit 53 with a trap 55, immersed in the refrigerant as Dry Ice 57, the trap preferably having a vacuum pump 59 at the exit thereof. Gases passing from the pump are preferably burned to remove all danger which may exist from a heavy carbon monoxide concentration. It is to be noted that vacuum conditions are not vital and that a sufiicient flow of carbon dioxide or other carrier gas may be maintained to continually force the gases through the apparatus. The trap is a safety measure for the collection of carbonyl which may possibly be carried with the exhaust gases through coil 49.

A desirable arrangement of the apparatus involves the provision of vessel 61 which houses plating chamber 17,

,the conduit 13 including the iron pent-acarbonyl and coil 7. The vessel is provided with an inlet line 63 and an outlet 65 for the passage of dry heated air. This air surrounds and contacts the noted members thus providing an. atmosphere which assists maintenance of uniform temperature conditions over the apparatus. The leads to the induction heater, the drive means for the eccentric, and the various piping arrangements may be passed through the vessel :walls in sealed relation therewith in any suitable manner, the same not being critical since the air temperature within the vessel will be about 150 P. which is sufiicient however to assist in attaining a high vapor pressure of the pentacarbonyl which boils at about The plated roving 24 in its exit from the plating chamber will also be benefited by the heat within vessel 61 since the temperature drop of the iron-coated fibers will be more gradual and thermal shock is thus avoided.

The untreated roving 24 is wound on a reel supported as at 67 and is initially passed through the apparatus in any suitable manner as by attachment to a tail. The plated material exiting from chamber 61 is wound on reel 69 fastened to a support 71 in any suitable manner by a bracket as at 73. Motor 75 having a pulley 77 over belt 79 drives the reel 69 to supply the motive power for the passage of the roving through the apparatus.

T he strand .34 passes from the reel into tank 89 over pulley 82 through a solution 34- and then to the heater 2.5. Drying and dehydration occur in the heater and plating chamber prior to metallic deposition on the fiber;

the heater may operate at any suitable temperature at which the heat decomposable metal bearing compound will deposit metal from the vaporstate, butit is -generally preferred that the heater be somewhat higher in temperature, as for example, with iron pentacarbonyl the heater 25 may operate at about 600 F.

The solution 84 may consist, for example, in parts by weight of:

Methacrylato chromic chloride 20 (Chromium 6) Isopropanol 45 Acetone 10 Water 169 This is the material which is marketed as Volan with parts of water added thereto.

The solute in appearance is a dark green liquid having a specific gravity of about 1.02 and a pH of approximatcly 1.8; the hash point is relatively low and care in handling is necessary, but diluted solutions as high as 9% of the material will not flash. When applied the solution is highly acid, preferably at a pH of about 4.0. Such material is available from Du Pont de Nemours & Co, The. under the trade name Volan.

When the mixture of carbonyl and carbon dioxide carrier contacts the heated chrome complex coating thermal decomposition of the iron on the filaments occurs and the gaseous products of decomposition flow on to coil 49. The amount of metal deposited varies with the volume concentration and time of flow of the carbonyl gas, the speed of the roving (1-309 feet per minute) and the various conditions may be regulated to produce any desired thickness of coating.

A suitable example of the conditions edective for the plating of iron carbonyl is as follows:

Example I Carbon dioxide flow through car- 2 liters per minute.

bonyl saturator (13).

Carbon dioxide flow through gas 0.5 liter per minute.

seal (37).

Fiber vibrator, R. P. M. (33)---- 500.

Vessel temperature (61) F. Carbonyl saturator temperature- 190 F. Fiber heater temperature (25)- 600 F. Fiber speed 40 ft. per minute. Carbonyl recycling condenser (49) 32 F. Dry ice trap (55) 70 F.

The example is set out as indicative only of the means of the application of the iron and is not to be considered as limitative of the invention.

Other metals may be employed in the same manner with the same beneficial results, particularly nickel; chromium itself as well as copper are also effective.

The corrosion resistant property of the film deposited by the decomposition of iron pentacarbonyl is useful in rendering the glass fiber conductive and in retaining the degree of conductivity constant. Apparently the CrO-Cr linkage developed on the surface of the glass by heating of the filament after treatment with the complex assists in attaining this conductivity retention feature.

it will be understood that this invention is susceptible to modification in order to adopt it to different usages and conditions and accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. In a gas plating process the steps of heating glass fiber material coated with a chrome complex of the Werner type in which methacrylic acid is coordinated with chromium, to a temperature at which a heat-decoin 'posable metal bearing compound thermally decomposes to deposit metal passing the so heated material into an enclosed zone, and at which temperature breakdown of the complex occurs without deformation of the fiber material and contacting the heated coated material in the enclosed zone with a metal carbonyl compound which is heat decomposable at that temperature.

2. In a gas plating process the steps of heating glass fiber material coated with a chrome complex of the Werner type in which methacrylic acid is co-ordinated with chromium, to a temperature at which gaseous heatdecomposable iron carbonyl thermally decomposes to deposit iron, and contacting the heated coated material with gaseous iron carbonyl to deposit iron on the coated material.

3. In a gas plating process the steps of heating glass fiber material, coated with a chrome complex of the Werner type in which methacrylic acid is co-ordinated with chromium, to a temperature at which gaseous heatdecomposable nickel carbonyl thermally decomposes to deposit nickel, and contacting the heated coated material with gaseous nickel carbonyl to deposit nickel on the coated material.

4. In a gas plating process the step of heating glass fiber material having an adsorbed coating thereon which coating results from the heating of methacrylato chromium chloride at a temperature of about 600 F., and then contacting the coated material with a heat decomposable metal carbonyl compound while the material is at a temperature of not greater than about 600 F. to deposit metal thereon.

5. In a gas plating process the step of heating a glass fiber material having an adsorbed coating thereon which coating results from the heating of methacrylato chromium chloride at a temperature of about 600 F. and then contacting the material with heat decomposable iron carbonyl to deposit iron thereon.

6. In a gas plating process the step of heating a glass fiber material having an adsorbed coating thereon which coating results from the heating of methacrylato chromium chloride at about 600 F. and then contacting the material with heat decomposable nickel carbonyl to deposit nickel thereon.

7. As an article of manufacture a strand of glass fiber material, a coating on the strand resulting from the heating at a temperature of about 600 F. of methacrylato chromium chloride while the same is on the fiber material, and a film of iron on the coated strand deposited by the thermal decomposition of gaseous iron carbonyl.

8. As an article of manufacture a strand of glass fiber material, a coating on the strand resulting from the heating at a temperature of about 600 F. a methacrylato chromium chloride while the same is on the fiber material, and a film of nickel on the coated strand deposited by the thermal decomposition of gaseous nickel carbonyl.

9. As an article of manufacture a strand of glass fiber material, a coating on the strand resulting from the heating at a temperature of about 600 F. a methacrylato chromium chloride while the same is on the fiber material, and a film of chromium on the coated strand deposited by the thermal decomposition of gaseous chromium carbonyl.

10. As an article of manufacture, a strand of glass fiber material, a coating on the strand resulting from the application thereto of methacrylato chromium chloride and heating the resultant coated strand to a temperature sufiicient to cause thermal decomposition of a gaseous metal carbonyl brought in contact therewith, and a film of metal on said coated strand deposited by the thermal decomposition of a gaseous metal carbonyl brought in contact therewith.

11. As an article of manufacture, a strand of glass fiber material, a coating on the strand resulting from the heating at a temperature of about 600 F. of methacrylato chromium chloride while the same is on the fiber material, and a film of metal on the coated strand deposited by the thermal decomposition of gaseous metal carbonyl.

References Cited in the file of this patent UNITED STATES PATENTS 2,470,378 Skala May 17, 1949 2,606,955 Herrick Aug. 12, 1952 2,616,165 Brennan Nov. 4, 1952 

1. IN A GAS PLATING PROCESS THE STEPS OF HEATING GLASS FIBER MATERIAL COATED WITH A CHROME COMPLEX OF THE WERNER TYPE IN WHICH METHACRYLIC ACID IS CO-ORDINATED WITH CHROMIUM, TO A TEMPERATURE AT WHICH A HEAT-DECOMPOSABLE METAL BEARING COMPOUND THERMALLY DECOMPOSES TO DEPOSIT METAL PASSING THE SO HEATED MATERIAL INTO AN ENCLOSED ZONE, AND AT WHICH TEMPERATURE BREAKDOWN OF THE COMPLEX OCCURS WITHOUT DEFORMATION OF THE FIBER MATERIAL AND CONTACTING THE HEATED COATED MATERIAL IN THE ENCLOSED ZONE WITH A METAL CARBONYL COMPOUND WHICH IS HEAT DECOMPOSABLE AT THAT TEMPERATURE. 